Despite considerable epidemiological and clinical trial data, the link between sodium intake and blood pressure control remains debated and poorly characterized, in part due to the degree of variability inherent in assessing dietary composition. By refining and applying new statistical methodology that addresses measurement errors, we propose to extend the analysis of existing data from the completed Trial of Nonpharmacologic Interventions in the Elderly to characterize relationships between blood pressure control and sodium intake (as measured by 24-hour dietary recalls and 24-hour urine excretion) using models that address the imprecision of these dietary measures; examine clinical and demographic factors that may affect this relationship and, in doing so, further characterize relative sodium sensitivity among a cohort of hypertensives; characterize the relationships between the intakes of other dietary factors (calcium, potassium, and magnesium) with blood pressure control; and examine the relationship between pharmacologic and dietary control of blood pressure among individuals prior to weaning from, and after resumption of, antihypertensive medications. Secondary aims include the application and further development of longitudinal measurement-error models for use in analyzing serial dietary data. The team of investigators for this project are well-qualified to conduct this scientific investigation, were instrumental in developing the TONE database, and have excellent resources.